Type Casting in C

What is typecasting?

Typecasting can be referred to as the conversion of one data type to another data type. It is also known as data conversion. There are two types of typecasting in C:

Implicit type casting
Explicit type casting

Let us define them one by one.

Implicit Type Casting:

This type of conversion takes place automatically when a value is copied to its compatible data type. It is actually defined as the conversion of data without losing its actual significance. Rules are followed strictcly, such as lower oder data type operands are automatically converted into high oder data type.

For Example:

#include<stdio.h>
int main(){
	short a=10; 
	int b;
	b=a;
	printf("%d\n",a);
	printf("%d\n",b);
	return 0;
}

Here at first a variable of short data type is initialised with 10, then the value of that variable is passed to a variable having integer data type. The statement of initialising the value as b=a is known as implicit typecasting.

Output:

Points to remember about implicit type casting:

Converting from smaller data type into a larger data type is called type promotion.
The implicit type conversion always takes place between compatible data types.

Converting float to an integer will truncate the fraction part, hence losing the meaning of the value in the variable.
Converting double to float will round up the digits.
Converting a long integer to an integer will cause the dropping of excess high order bits.

Explicit Type Casting:

In implicit type conversion, the data type is converted automatically. In some cases force type conversion are made, such forced type conversion comes under explicit type casting.

Syntax For Explicit Type Casting:

(type name) expression;

In this case the type name is initialized with the data types present in C, where as the expression is initialised with expressions, constants or variables.

For example:

#include<stdio.h>
int main()
{
	float a = 1.2;
	int b = (int)a;
	printf("Value of a is %f\n", a);
	printf("Value of b is %d\n",b);
	return 0;
}

Here, the variable a of float data type is initialized and the it is forced type casted to the variable b of integer data type. This force type casting is called explicit type casting.

Output:

Arithmetic Conversion Hierarchy:

The compiler first proceeds with promoting a character to an integer. If the operands still have different data types, then they are converted to the highest data type that appears in the following hierarchy chart: